Temperature and Growth Selection Effects on Proliferation, Differentiation, and Adipogenic Potential of Turkey Myogenic Satellite Cells Through Frizzled-7-Mediated Wnt Planar Cell Polarity Pathway

Abstract

Satellite cells (SCs) are a heterogeneous population of multipotential stem cells. During the first week after hatch, satellite cell function and fate are sensitive to temperature. Wingless-type mouse mammary tumor virus integration site family/planar cell polarity (Wnt/PCP) signaling pathway is significantly affected by thermal stress in turkey pectoralis major (p. major) muscle SCs. This pathway regulates the activity of SCs through a frizzled-7 (Fzd7) cell surface receptor and two intracellular effectors, rho-associated protein kinase (ROCK) and c-Jun. The objective of the present study was to determine the effects of thermal stress, growth selection, and the Fzd7-mediated Wnt/PCP pathway on proliferation, myogenic differentiation, lipid accumulation, and expression of myogenic and adipogenic regulatory genes. These effects were evaluated in SCs isolated from the p. major muscle of 1-week faster-growing modern commercial (NC) line of turkeys as compared to SCs of a slower-growing historic Randombred Control Line 2 (RBC2) turkey line. Heat stress (43°C) increased phosphorylation of both ROCK and c-Jun with greater increases observed in the RBC2 line. Cold stress (33°C) had an inhibitory effect on both ROCK and c-Jun phosphorylation with the NC line showing greater reductions. Knockdown of the expression of Fzd7 decreased proliferation, differentiation, and expression of myogenic regulatory genes: myoblast determination factor-1 and myogenin in both lines. Both lipid accumulation and expression of adipogenic regulatory genes: peroxisome proliferator-activated receptor-γ, CCAAT/enhancer-binding protein-β, and neuropeptide-Y were suppressed with the Fzd7 knockdown. The RBC2 line was more dependent on the Fzd7-mediated Wnt/PCP pathway for proliferation, differentiation, and lipid accumulation compared to the NC line. Thus, thermal stress may affect poultry breast muscle growth potential and protein to fat ratio by altering function and fate of SCs through the Fzd7-mediated Wnt/PCP pathway in a growth-dependent manner.

Transcriptome response of proliferating muscle satellite cells to thermal challenge in commercial turkey

“…This nuclear protein is a muscle-specific transcriptional regulatory factor. Similar findings for MYOD1 expression were observed in our previous studies ( Reed et al, 2017a ; Xu et al, 2022 ). Like MYOD1 , significant upregulation in response to heat stress was seen for DLL1 in both RBC2 and NCT SCs (Log 2 FC = 2.13 and 2.72, respectively).…”

“…Myogenin is required for differentiation and the formation of multinucleated myotubes. This up-regulation is consistent with the findings of Xu et al (2022) who measured MYOG expression by qRT-PCR. Also consistent with Xu et al (2022) , we observed slightly reduced expression of the peroxisome proliferator-activated receptor PPARγ in both lines with heat stress.…”

“…This up-regulation is consistent with the findings of Xu et al (2022) who measured MYOG expression by qRT-PCR. Also consistent with Xu et al (2022) , we observed slightly reduced expression of the peroxisome proliferator-activated receptor PPARγ in both lines with heat stress. Expression of myogenic factor 6 ( MYF6 [ MRF4 ]), trended slightly lower with heat stress (Log 2 FC = −1.83 and −1.37 in RBC2 and NCT, respectively).…”

“…Up regulation of Wnt7a during the period of SC peak mitotic activity, suggests that thermal stress affects turkey skeletal muscle through a similar mechanism. Supporting evidence is provided by knockdown experiments where in the same cultured 1-week turkey SCs used in this study, knockdown of Fzd7 significantly decreased proliferation and MYOD expression especially under heat stress (Xu et al, 2022). The NCT SCs being less affected than RBC2 SCs.…”

Why breast muscle satellite cell heterogeneity is an issue of importance for the poultry industry: An opinion paper

“…Muscle mass accretion is a result of satellite cell-mediated growth and these functional differences in satellite cells will impact muscle growth and subsequent meat quality of the breast muscle. Furthermore, Xu et al (2022a , b) showed satellite cells, based on their growth potential, have differences in their regulation of signal transductions pathways like mechanistic target of rapamycin (mTOR) and wingless type mouse mammary tumor virus integration site family/planar cell polarity (Wnt/PCP) pathways. Mechanistic target of rapamycin signal transduction is a key pathway involved in muscle fiber hypertrophy and Wnt/PCP is involved with satellite cell proliferation and differentiation, and lipid synthesis.…”